SpaceX launches its first refurbished Dragon cargo ship to the space station

SpaceX took one more step in its campaign for rocket reusability today by sending a previously flown Dragon cargo spacecraft to the International Space Station for the first time.

If all goes well, it should mark the first space station rendezvous for a reused spaceship since the retirement of NASA’s space shuttle fleet in 2011.

SpaceX’s Falcon 9 rocket lifted off at 5:07 p.m. ET (2:07 p.m. PT) from Launch Complex 39A at NASA’s Kennedy Space Center in Florida. An earlier countdown on Thursday had to be called off when a lightning storm struck too close to the launch pad.

It was the 100th launch from Pad 39A, which has been the starting point for space journeys going back to the Apollo moon shots.

Hans Koenigsmann, SpaceX’s vice president of mission assurance, said that he was “super-happy, as always, after a good launch” – and that it felt great to be a part of Pad 39A’s 100th launch.

The robotic Dragon capsule is loaded up with nearly 6,000 pounds of experiments and supplies for the station and its crew.

Among the payloads are carriers packed with 40 mice for in-orbit experiments aimed at testing therapies for bone loss, which is a serious problem for long-term space travelers. Twenty of the mice will be returned to Earth on a future Dragon flight for extended study.

There’s also a fruit fly experiment aimed at studying heart function, which is another health concern for astronauts. Other experiments focus on protein crystal growth and plant growth in zero-G.

The Dragon’s unpressurized “trunk” is carrying an experimental set of roll-out solar arrays, a precision pointing platform for Earth observation and an experiment that will be mounted to the station’s exterior to study neutron stars.

SpaceX’s billionaire founder, Elon Musk, has long sought to develop reusable spacecraft as part of his strategy to reduce the cost of access to space – and this mission marks another advance for the quest.

Over the past year and a half, SpaceX has gotten the knack of having its Falcon 9 first-stage boosters fly themselves back for landings and recoveries. Today, the booster touched down at SpaceX’s Landing Zone 1 in Florida, not far from the launch pad, with a fusillade of sonic booms heralding its arrival.

The Dragon capsule launched today for the CRS-11 mission previously flew on the CRS-4 space station resupply mission in 2014. After its splashdown, the Dragon was inspected and refurbished for reuse, with components replaced as necessary.

“This is the first time when we fly actually the hull, the structure of Dragon and the majority of components again,” SpaceX’s Koenigsmann said in a pre-launch NASA interview. “That lines up well with our quest of reusability and overall, in the long term, lowering the cost of access to space.”

Koenigsmann said it’s “a pretty big deal.”

The space shuttle orbiter was also reusable, but there’s a big difference in the cost: By some estimates, each shuttle flight cost as much as $1 billion. The price tag for each SpaceX Dragon resupply flight is in the neighborhood of $133 million, based on the terms of the company’s contract with NASA.

The Dragon is due to rendezvous with the station on Monday. To make room, a robotic Orbital ATK Cygnus cargo craft, filled with trash, will be unhooked from the station on Sunday for disposal.

When Dragon shows up, astronauts will use the station’s robotic arm to pull it in for its berthing. Over the course of the following several weeks, they’ll unload the cargo, load it back up with payloads destined to be sent to Earth, and then prepare it for its descent to a Pacific Ocean splashdown.